Aug. 8 is World-Cat Day, also known as International Cats Day. The event was founded in 2002 by the International Fund for Animal Welfare and other animal rights groups, according to the Cute Calendar.(Yes there is such a thing as a "cute calendar"!)

In honour of this sacred day, here is a list of some of the more famous cats on the Internet.

Grumpy Cat

Probably the most famous cat on the Internet is Grumpy Cat. Born on April 14, 2012, the cat was given the name Tardar Sauce by its owner Tabatha Bundesen. But the cat became a meme known as Grumpy Cat when photos were posted to Reddit in September 2012. The permanent grumpy expression on its face is due to feline dwarfism and an under bite.

Now Grumpy Cat has appeared on various TV programs, such as the Today Show, Good Morning America, American Idol and The Bachelorette. There were even rumours, or at least a joke video by Mashable, that the cat was going to replace David Letterman.

Grumpy Cat also has tons of merchandise from mugs to shirts to plush toys even a book. It was named 2012's most influential cat by MSNBC, got BuzzFeed's Meme of the Year Award at the 2013 Webby Awards and the Golden Kitty at the second annual Internet Cat Video Film Festival.

It has also won a Lifetime Achievement Award at the 2013 Friskies, for which it has appeared in several online commercials.

On June 11, 2014, Lifetime announced it will be producing Grumpy Cat's Worst Christmas Ever a TV movie about the cat.

Lil Bub

Second only to Grumpy Cat is Lil Bub. Born on June 21, 2011, this cat also became famous to due physical anomalies, giving it a unique disposition. Like Tardar Sauce, Lil Bub has feline dwarfism but also has a shorter lower jaw with no teeth so its tongue hangs out, giving it a permanent panting expression. In addition, it has osteoperosis and polydactylism (meaning it has extra toes on its paws).

Photos of the cat were first posted to Tumblr in November 2011 and then went viral on Reddit. And it also has videos on its YouTube channel.

Lil Bub has also appeared on various TV shows, such as Good Morning America and The View, has appeared in Bullet and Bloom magazines and has a book.

Its documentary Lil Bub & Friendz (which also featured Grumpy Cat) debuted at the Tribeca Film Festival on April 18, 2013.

Hamilton the Hipster Cat

Hamilton the Hipster Cat get its name from the white fur over its lip giving the look of a moustache.

As its Facebook page states, it "has a real mustache that is better than any mustache that has ever walked this planet."

Indeed, it does. It's certainly better than most moustaches you find on someone in the steam punk community.

The page also says that Hamilton the Hipster Cat was likely born on July 4, 2012.